We have shown that cellular levels of arylsulfatases A and B in chondrocyte cultures derived from normal and osteoarthritic articular cartilage were reduced in the presence of vitamin C. The decrease in activities was proportional both to the concentration of ascorbic acid in the nutrient media and to the length of time that the cells had been exposed to the vitamin. Ascorbic acid also caused an increase in the biosynthesis of sulfated proteoglycans per unit of DNA. Furthermore, the distribution of the newly synthesized macromolecules was altered and a larger fraction of them was deposited in the cell layer of the cultures. The vitamin did not cause cell damage since the effects were reversible. To see how these observations extend to an in vivo system and to evaluate whether vitamin C could be used to increase the stability of proteoglycans in osteoarthritic articular cartilage, we propose to monitor the effects of increasing levels of ascorbic acid on sulfated proteoglycan metabolism and arylsulfatase activities in the knee joints of guinea pigs in which osteoarthritic lesions have been induced by the surgical division of the anterior cruciate ligament. Experimental and control animals will be placed either on a vitamin C - deficient, normal, or highly enriched diet. Vitamin C levels of the animals' sera will be monitored routinely. At periodic intervals post-surgery, the articular cartilage from the operated and control knees of animals in each diet group will be removed and examined macro- and microscopically for osteoarthritic lesions. The remainder of the tissue and, where applicable, the synovial fluid will be analyzed for arylsulfatase and acid phosphatase activities, DNA and protein content, and sulfated proteoglycan biosynthesis. This research is directed toward a better understanding of the effect of vitamin C in articular cartilage and the physiological relationship between arylsulfatase activities and sulfated proteoglycan stability in the matrix of this tissue.